GENETIC ANALYSES OF SALMONELLA TYPHIMURIUM × ESCHERICHIA COLI HYBRIDS

Abstract

An analysis has been made, by transduction experiments with Salmonella typhimurium mutants and S. typhimurium X Escherichia coli hybrids, of a region covering about one tenth of the bacterial genome (about ten transducing fragments). Phage P22 can carry, without discrimination, fragments that are wholly Salmonella in origin, wholly E. coli, or a composite of both. Genetic material from E. coli fragments is incorporated into Salmonella recipient chromosomes with a frequency about 1 per cent that of the integration of material from Salmonella fragments. It is proposed that a low degree of homology between the two bacterial genomes, at the molecular level, is responsible for the low frequency of integration.